Load frames, in addition to shaping and stiffening the fuselage of an aircraft, are the structural elements in charge of withstanding and transferring the loads coming from other structural elements of the aircraft, e.g. the wings or the stabilizers.
Traditionally, load frames have been made of metallic material and with different sections, the most usual ones being C-, I- and J-sections which, through machining processes, form a ribbed framework that stabilizes the web of the frame.
In today's aeronautical industry, the strength-to-weight ratio is an element of utmost importance; therefore, there is a demand for frames manufactured or optimised with composite materials, primarily with carbon fibre, instead of metallic frames.
In the case of load frames, it is difficult to compete with machined metallic frames because, due to the high and differing stresses they must withstand, alternative frames in composite materials usually pose various manufacturing problems since their design is so complex. In any event, some proposals are now available in this respect, such as those described in the applications for patents WO 2008/092970, US 2009/0026315 and WO 2009/030731.
One of the aforementioned problems is related to the attempt to achieve a frame design in which the webs are stabilized, thus making it possible to optimise the weight. Although in the case of form frames there are now some proposals available, the same is not true of load frames in spite of the existing demand for them in the aeronautical industry.
This aim of this invention is to address this demand.